This invention relates to an improved process for the preparation of a beta phase of molybdenum trioxide or the isostructural mixed metal oxides of molybdenum and tungsten.
Molybdenum trioxide (alpha) is known to crystallize with a two dimensional structure, which has been described as a layered structure, MoO.sub.1/1 O.sub.2/2 O.sub.3/3, or as a chain structure, MoO.sub.2/1 O.sub.2/2. Tungsten trioxide is known to adopt a ReO.sub.3 -related structure, WO.sub.6/2. The dissimilar structure of alpha MoO.sub.3 is believed to be caused by the formation of oxomolybdenum cations which stabilize the layered structure. Novel phases of molybdenum trioxide and mixed metal-oxides of molybdenum and tungsten and methods for their preparation are of interest to the chemical industry.
U.S. Pat. No. 4,753,916 discloses methods for preparing a composition of matter comprising .beta.-Mo.sub.l-x W.sub.x O.sub.3, wherein 0.ltoreq.x&lt;1.0. One method of the invention comprises spray-drying a solution of molybdic acid or molybdic and tungstic acids in appropriate concentrations and heating the resulting powder to a temperature of about 275.degree. C. to about 450.degree. C.
U.S. Pat. No. 4,753,916 also describes the properties and the utilities of these beta phase materials. The disclosures of this patent are hereby incorporated by reference.